Monthly Archives: March 2006 - Page 3

Technically Tapping

If you’ve ever wondered how the technical side of wiretapping works this NetworkWorld article is for you.

The most common type of tap is a pen register (otherwise known as trap and trace), which produces a log showing what numbers were called, and the dates, times and durations of the calls. The second type intercepts the content of the call.

Without going into excruciating detail this article gives an excellent overview of the types of wiretapping and how each type is accomplished. Some relevant laws and tapping methods for data networks are also discussed. If you’re unfamiliar with wiretapping technology this article provides a great jumping off point for further research.

From the Trenches

One of the things I enjoy collecting are tech support calls where the user makes a complete fool out of themself. I’ve got an interesting and enlightening collection of those. Along the same lines are some of these real stories from tech support recently published in NetworkWorld.

“You have to have a good sense of humor to work at this,” says Jeff Whitmore, director of IT at guitar strings and accessories maker Ernie Ball of San Luis Obispo, Calif.

“My favorite request is from people wanting me to ‘Restart the Internet [because] it seems frozen,'” he says. “I’m going to quit the day I stop laughing at some of the things people think we should and can do.”

With users like this who needs TV comedy?

Old Apple Software

Apple Computer has a great web site with links to old drivers, software updates and even operating systems. Stretching back to the Apple II days and up to just before OS 8 this is quite the treasure trove for a vintage Macintosh collector such as myself. Heck, they even have updates for the ill-fated Newton PDA operating system should you be so lucky as to have one of those.

Songs about Phsyics

Sometimes what feels so right is so very wrong. Walter F. Smith Associate Professor of Physics at Haverford College has a website called Naturally, the site features lyrics about physics set to your favorite tunes ranging from “Twinkle, Twinke, Little Star” to the “Macarena”. If you’re really a glutton for punishment you might check out the first ever physics song sing-a-long taking place at the March 15 annual meeting of the American Physical Society in Baltimore, MD. Oh, the website is very bright and reminiscent of those 1990s websites you just love to hate.

Distributing Bandwidth Costs

If you haven’t yet read Bob Cringely’s latest column you’ll find it to be an interesting vision for content distribution in the future. Diving right into the problem of bandwidth for video distribution over IP Bib comes to the conclusion that peer-to-peer technology will be the savior of the content holders in the end preventing them from needing to purchase obscene amounts of bandwidth.

Interestingly I came to the conclusion about a third of the way through the article that he explores further right towards the end. The way to encourage people to share their bandwidth via P2P is to pay them for it. Bob mentions “Peer Impact” which is a content company and software program that has currently adopted a model similar to this. I would take this one step further and say that there is a business model for some company to create a peer-to-peer network which pays each user on a per-megabyte of transfer they do for the network and then turns around and resells that bandwidth to content creators who need bandwidth. If you think about it this is a much more efficient system than the top-down system currently in place. It also solves one of the biggest problems with widespread BitTorrent, etc. systems which is that people leech from the system and then disconnect before returning their fair share of the bandwidth. If people were being paid to simply run a P2P client in the background, one which was agnostic about what was being transferred (eg. you would not have to intentionally download the content yourself first, it would all be automatic), you wouldn’t have a problem with people keeping the client open because they would see it as a moneymaking opportunity which costs them nothing. The ISPs will probably grumble at first but in the end they would come around because it saves them internet bandwidth if the content can move around within their network instead. What you’re really setting up in this scenario is a content distribution and caching system where people dedicate some of there hard drive towards caching content that is currently in demand and then sharing that content with other subscribers on the network. I think there’s a real business potential in this market so if you capitalize on this idea please remember where you got it.

One other issue Bob mentions is the distribution of live streaming content. He seems to see this as some sort of unresolved problem. While it’s true that most P2P systems don’t handle live content very well there is another solution. For years Cisco has been promoting IP Multicasting as a way to conserve a lot of bandwidth for live streaming broadcasts. Unfortunately, the technology is still not widely implemented. If the major backbone carriers and ISPs made a big push to support multicasting on all their routers content creators would only have to push one stream out to the internet where routers would distribute it globally. It’s really a well thought out solution but more people need to get on board. Strangely enough Cringely doesn’t even mention multicasting which leads me to believe this technology is still very much under the radar even though it has been used on some private networks for years.

Radio over VoIP

In a followup to an earlier article about the Cisco IPICS system I have received some additional information that seems to indicate my preliminary analysis was correct. If you remember when Cisco launched their IPICS ’emergency communications system’ I suggested it was really more of a way to tie existing communications systems together than a new system itself.

It seems that Cisco has been looking into this for a while and ostensibly created this product to fill an internal company need for connecting disparate communications systems. This case study explains how Cisco created a Land Mobile Radio (LMR) over IP product to fill a need to communicate with their own security personnel. The end product is described in this Cisco whitepaper entitled “Cisco Land Mobile Radio over IP Solution Reference Network Design”.

The LMR over IP product is a card which can be installed in any of the voice capable Cisco routers and provides an interface that connects full-duplex VoIP datastreams to speaker, mic, push-to-talk (PTT) half-duplex devices. Signaling is via standard H.323 and the card uses RTP audio with a variety of codecs. The card used is called a VIC Ear and Mic (E&M) interface and was originally used to connect VoIP to some legacy PBX hardware. Technical information about the E&M interface can be found in this technical publication. If your LMR equipment supports a half-duplex T1 that can be used as a trunk interface instead.

As a friend pointed out the existence of support for this type of configuration presents some interesting ideas for amateur radio VoIP projects. Without going into too much detail the current preferred methods of connecting amateur radio stations with VoIP is to use either the Echolink or IRLP project. Both of these have a significant number of problems, one of which is that they require a computer to be attached to the radio. It would be much nicer to attach a (more stable) router to the radio instead. This merits some more research. Once you got a radio attached to a VoIP phone system such as Asterisk there’s all kinds of interesting possibilities.